Obesity occurs disproportionately in women of lower socioeconomic status (SES), especially in industrialized countries. Rising rates of obesity have been linked to higher rates of cardiovascular disease, cancer, diabetes, and other chronic and life threatening diseases in both men and women. Weight gain in women during middle age (age 30-50) is frequent and of particular concern because of the consequences for later health and because of the important role these women play in their households. Among Hispanics, higher rates of obesity are associated with higher SES, similar to what has been found in poorer countries, historically. Most obesity prevention programs based on individual behavior change have not been successful in achieving long-term healthy weight. Attention is shifting to more complex environmental and societal contributions to adiposity, including central adiposity, to help identify multi-level and multi-causal pathways and to target interventions to high risk groups. Improved understanding is needed of the mechanisms by which established risk factors for increased body mass index (BMI) operate along the SES gradient (inverse for Caucasians, and positive for Hispanics). The main aim of this project is to better understand and evaluate the putative causal pathways between SES and BMI in middle-age women. Data from this project would assist in reducing the number of intervention channels and provide clues on how to reach these women and their household members to influence weight change through the mechanisms that mediate the SES disparities in risk of obesity. Ultimately, excess weight is caused by energy imbalance, with higher caloric input than output. However why this should occur at different rates according to different levels of SES is not known. We shall test key explanations for the SES and overweight/obesity relationship in a population-based cohort of 1000 women age 30-50, with oversampling of Hispanic women in a major urban area, based on a conceptual model by Mackenbach.1-3 By augmenting the recruitment to enhance the representation of women of Hispanic ethnicity, we will be able to conduct analyses within the group who are non-Hispanic white and separately, within the group who are of Hispanic origin. Specific aims are as follows: 1. To evaluate the mediating cross-sectional effects of a) material resources (e.g., walkability of neighborhood, availability of healthy foods; cost of food); b) psychosocial context (e.g., body image, norms of family and culture);and c) stress process (e.g., mood, sleep disturbance, cortisol) in the relationship between SES, weight-related behaviors (physical activity & eating patterns) and BMI in middle-age women 2. To evaluate the relationship between SES and change in weight over a 3-year period 3. To evaluate longitudinally the mediating effects of material resources, psychosocial context, and the stress process in the relationship between SES, BMI and central adiposity in middle aged women. PUBLIC HEALTH RELEVANCE Possible explanations for the observation that gradients over time in increased weight for height differ according to socioeconomic status are not well understood, and may differ by ethnicity or other socio- cultural factors. We propose, in middle aged Caucasian and Hispanic women, to study mechanisms including social, psychological, and biological factors, and the intersection of these factors in explaining the observed associations of obesity risk with socioeconomic status. Data from this project would assist in reducing the number of intervention foci and provide clues on how to reach these women and their household members to influence weight change through the mechanisms that mediate the socioeconomic disparities in risk of obesity.